South Korea has successfully test-fired two domestically built ballistic missiles that can hit any target throughout North Korea, making it a crucial part of the South's defense against its neighbor's nuclear and missile capabilities, the president's office said on Wednesday.

Reuters reports President Park Geun-hye made a rare visit to a missile base on the west coast to watch the launch of the missile, which was developed under a new agreement with the United States. According to the 2012 deal, South Korea is permitted to possess ballistic missiles with a range of up to 500 miles in response to North Korea's continued nuclear and missile threats.

"The test demonstrated improved ballistic missile capability that can strike all parts of North Korea swiftly, and with precision, in the event of armed aggression or provocation," the presidential Blue House said in a statement.

The missiles, which have a reported range of over 300 miles, were fired from a southern launch pad. The Independent notes that there was no clear or immediate response from North Korea, which is heavily sanctioned for its past long-range rocket and nuclear tests. In March, the North's military fired two short-range ballistic missiles into the sea in response to naval drills carried out by the U.S. and South Korea, heightening concern that Pyongyang is working on other means to launch attacks. The North also claimed it is developing further nuclear weapons with intercontinental reach.

The annual drills carried out by the U.S and South Korea have previously angered North Korea, which sees them as a threat to its national security despite the South's claims that the military exercises are focused only on defense.

"The only means to cope with the aggression and war by the U.S. imperialists and their followers is neither dialogue nor peace. They should be dealt with only by merciless strikes," an unidentified spokesman for the North Korean military's general staff said in a statement carried by state media.

According to the Korea Times, the military plans to deploy the weapon to a "subunit of the Army's missile command by the end of the year" following the successful test-fire. 

Additionally, South Korea and the United States have established four principles for counter-missile operations that will guide alliance decision-making, capability development, and operations, according to "Strategic Digest 2015." Currently, some 28,500 US troops are stationed in South Korea to defend the country in case of attack from the North, including the threat of nuclear warfare.